Apparatus for manufacturing reinforced tubings from plastic materials

ABSTRACT

In the manufacturing of tubings from rubber or other plastic materials the steps of continuously extruding a first inner layer of the tubing wall in an extruder head over a guide serving to form the cavity of the tubing, continuously applying strand-like reinforcing material through feed passages onto the outer surface of the wall part forming in such way and still in plastic state and then coating this reinforced inner wall part by at least one further layer of a plastic substance, to thereby provide tubings containing a reinforcing lining in the wall material to give reinforcement against internal pressures.

United States Patent Schiesser 1451 Oct. 10, 1972 [54] APPARATUS FORMANUFACTURING REINFORCED TUBINGS FROM PLASTIC MATERIALS [72] Inventor:Walter Hugo Schiesser, Zurich,

Switzerland [30] Foreign Application Priority Data Sept. 20, 1968Austria ..9172/68 [52] US. Cl. ..425/l09, 264/173, 425/114, 425/133 [51]Int. Cl. ..B29f 3/04, B29f 3/10 [58] Field of Search ..l8/l3 R, 13 D, 13E, 13 H, 18/13 J, 13 K, 13 P, 13 S, 13 T, 14 G, 14 R, 14 P; 264/173;138/138, 174

2,874,411 2/1959 Berquist ..l8/l3 R ux 3,405,426 10/1968 Donald ..18/13H 2,760,230 8/1956 Van Riper ..l8/13 11 3,058,493 10/1962 Moller ..18/l3H ux 3,365,750 1/1968 Donald 18/14 P x Primary Examiner-J. SpencerOverholser l Assistant Examiner-Norman E. Lehrer Attorney-Wood, Heron &Evans [57] ABSTRACT In the manufacturing of tubings from rubber or otherplastic materials the steps of continuously extruding a first innerlayer of the tubing wall in an extruder head over a guide serving toform the cavity of the tubing, continuously applying strand-likereinforcing material through feed passages onto the outer surface of thewall part forming in such way and still in plastic state and thencoating this reinforced inner wall part by at least one further layer ofa plastic substance, to thereby provide tubings containing a reinforcinglining in the wall material to give reinforcement against internalpressures.

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APPARATUS FOR MANUFACTURING REINFORCED TUBINGS FROM PLASTIC MATERIALSThe present invention relates to a method of manufacturing tubings fromrubber or other plastic materials, which are provided with a reinforcinglining in the wall material to give reinforcement against internalpressures, as well as to an extruder head for carrying out the method.

Such tubings containing reinforcing linings or layers, particularlyfabric-reinforced tubings, are today manufactured according to variousconventional methods. The known methods for manufacturing such tubingsrequire, however, a time-consuming, complicated and costly process ofproduction and much preparation work. Moreover, corresponding mechanicalequipment is necessary to this end. A main feature of the conventionalprocesses of production is that a so-called core must firstly beextruded as tubing, on which a reinforcement or lining composed offabric-ribbon or threads is applied in a separate working step and withspecial machines (ribbons with ribbon machine, braid with braider orweaving frames) and the outer tubing is then extruded, in a secondstage, through a cross head by means of an extruder. This operation isrepeated according to the desired number of fabric reinforcements orlinings in the wall of the tubing. In order to obtain a good connectionbetween ribbon or reinforcing thread, a glue solution must as a rule bespread on after these reinforcements have been applied. In most cases itis also necessary that the inner tubing (core) is fitted on a long metalcore before passage through the machine applying the fabricreinforcements or linings.

It is clear that this fabrication, made up of many working stages,represents a time-consuming procedure and also involves correspondinglyhigh costs.

It is an object of the present invention to provide a method whichenables tubings containing reinforcing linings to be manufactured fromrubber or other plastic materials in a single working stage, asubsequent vulcanization also being possible by a continuous vulcanizingprocess (eg salt bath, high frequency vulcanizing furnace etc.). i

According to the present invention, the method is characterized-in thata first inner layer of the tubing wall is continuously extruded in anextruder head over a guide serving to form the cavity of the tubing, inthat strand-like reinforcing material is continuously applied in thelongitudinal direction of the tubing on the outer surface of the wallpart formed in this way and still in plastic state and the whole beingthen coated by at least one further layer of .a plastic substance.

It is particularly advantageous if further strand-like reinforcingmaterial is fed at approximately the same time as the extrusion of theplastic substance for the outer layer of the tubing wall, viz. at agreater radial distance from the center of the tubing than the'firstreinforcing material, whereby this further reinforcing material isembedded in the material of the outer layer of the tubing wall. In thisway, two layers of the reinforcing or lining material are obtained.Ribbons made of textile material or even metal wires may advantageouslybe used as reinforcing material.

According to another object of the invention, the extruder head forcarrying out the method consists of a housing having at least oneconnection for a plasticizing unit in which the means for forming thetubing are provided, is characterized in that the tubing forming meansconsist of a mouthpiece with a central bore, on whose inlet side isprovided a first chamber from which plastic substance used for formingthe inner tubing wall part is extruded into the annular space betweenthe bore wall and a guide passing through the bore and serving to formthe cavity of the tubing, in that feed channels for the strand-likereinforcing material pass through the mouthpiece body to the centralbore, in that at least one further chamber is provided on the outletside of the mouthpiece from which further plastic substance isextrudable onto the already formed tubing wall part, which chamber isclosed on the side opposite the mouthpiece by a disc having a centralbore, the central bore of the disc through which the means for formingthe tubing cavity also pass, being arranged coaxially to that of themouthpiece and serving to give the tubing its outer contour.

The guide serving to form the tubing cavity advantageously consists of acylindrical core passing through the first chamber, the central bore ofthe mouthpiece and through the closure disc of the second chamber to theoutlet of the extruder head.

An extruder head of this type is particularly advantageous in which themouthpiece is provided with feed channels for ribbonor thread-likereinforcing material, which channels pass through the bore wall into thecentral bore in two radial planes lying at a distance from one another,the channels of the second plane, observed in direction of transit ofthe tubing,

opening into a section of the bore with an enlarged- FIGS. 4-9 showdifferent views, also on a larger scale and partly in section, of theindividual parts of the mouthpiece, and

FIG. 10 shows purely schematically a cross-section through a tubingmanufactured by means of the extruder head according to FIG. 1.

Referring now to the drawings, P16. 1 shows a cross extruder head formanufacturing tubings containing v reinforcing layers. The extruder headis connectable to an extruder (not shown) by means of part 2 of itshousing 1. In the rear part of the housing 1 is provided a cone 3through which two interfitting excentric sleeves 4 and 5 pass forwardly.A core 6 having a conically shaped foot part 7 is screwed into the frontend of the sleeve 5. The two excentric sleeves 4, 5, which are fixableby screws 8, 9, enable the core 6 to be radially adjustable to a certaindegree, i.e., the inner tube part formed over the core 6 may be heldexactly in center.

The core passes through a first chamber 10 which is connected viapassages (not shown) with the material feed-in bore 11 of the part 2 ofthe housing. Adjacent this first chamber is provided .the mouthpiece 12,which is secured to a holder 14 by means of a sleeve 13. The mouthpiece12 through which the reinforcing ribbons are fed, will be described ingreater detail hereinbelow..A second chamber 15, which is connected withthe chamber 10 via passages 16 of the ring 14, is located infront of themouthpiece 12. A disc 17 having a central bore 18 is provided as closurefor the chamber 15. This disc 17 gives the tubing its outer contour. Thedisc 17 is secured in a sleeve 19 and is adjustable in a radial plane bymeans of at least three screws 20 (only two of which have been shown).In this way, the outer tubing may be centered.

A first inner tubing wall part, the so-called inner tube, is formedbetween the core 6 and the wall of the longitudinal bore 21 of themouthpiece 12, for which part of the plastic substance from the chamber10-is used. Reinforcing ribbons are fed through a number of channels 22which pass through the mouthpiece 12 at an angle with respect to thelongitudinal axis thereof, in order to open into the bore 21 ina firstradial plane, and said ribbons are applied on the continuouslyforming,forwardly passing inner tube.

More feed-channels 23 for reinforcing ribbons open into the bore 21,whose diameter is somewhat enlarged at this point, in a radial planelocated somewhat further forward when observed in the direction oftransit of the tubing. Somewhat at the samev point, plastic substancewill also penetrate from the chamber into the space between'the alreadyformed inner tube and the wall of the enlarged bore 21 and thereinforcing ribbons emerging from the channels 23'are thus embedded. Atthe outlet of the mouthpiece, the last-named ribbons are again coveredwith more plastic substance and completely embedded therein.

In the housing 1 and ring 14, axial bores 24 or 25 are arrangedto berelatively shifted in peripheral direction, through which thereinforcingribbons can be fed to the channels 22 and 23. The channels 22 and 23 ofthe mouthpiece 12, as well as the bores 24, 25 are so arranged that theribbons emerging on two different diameters (observed in cross-sectionof the bore 21 or of the forming tubing) lie uniformly shifted withrespect to one another, i.e., the ribbons of the second layer lie abovethe spaces in the first layer of ribbons and thereby partly cover theribbons of said firstlayer. Thanks to this arrangement, the plasticsubstance from the chamber 15 can penetrate thoroughly between and underthe ribbons of the channels 23 and form an excellent connection with theinner tube which is still in a plastic state.

FIG. 10 of the drawing best shows what a tubing formed in this mannerlooks like. On the first layer of the tubing wall, i.e., the inner tube26, are located six reinforcing ribbons 27 spaced uniformly with respectto one another. On a somewhat larger radius and exactly above thespacesbetween the ribbons 27, are provided six further reinforcingribbons 28. Said. ribbons are completely embedded in the substance 29forming the outer partof the tubing. Such a simply manufactured tubinghas a very high strength. All parts of the tubing are tightly connectedtogether without the reinforcing layers having had to be speciallyprepared before.

Of course, the chambers 10 and 15 of the extruder head could be fed fromtwo separate extruders, i.e., the chambers could be charged withdifferent materials. This would enable a tubing to be manufactured inone working stage whose inner part could consist for example ofoil-resistant material and whose outer part could consist for example ofozone-resistant material.

FIGS. 2-9 show the different individual parts of the mouthpiece 12.

As may best be seen from FIG. 2, the mouthpiece 12 consists of threeparts, namely a rear, central and front part 30, 31 and 32 respectively.

Six guide grooves 34 for reinforcing ribbons, are provided on theconical face 33 of the rear part 30 at a distance of 60 with respect toone another. The width of the grooves 34 is somewhat larger than thewidth of the ribbons themselves (see FIGS. 4 and 5, FIG. 5 showing aview in direction of arrow B of FIG. 4).

FIGS. 6 and 7 show the central part 31 of the mouthpiece 12, viz. FIG. 7is a view in direction of arrow C of FIG. 6. The feed channels 22 forthe inner layer of the reinforcing ribbons are formed in assembled state(see FIGS. 1, 2 and 3) between the conical face 35 of part 31 and thegrooves 34 of the face 33 of the part 30. The section 21' of the bore ofthe part 31 forming a part of the longitudinal bore 21 has a diameterenlarged by about twice the thickness of the fed ribbons. Six furthergrooves 37 are provided on the likewise conical outer face 36 of thepart 31. However, in assembled state, saidgrooves will be angularlyoff-set with respect to the grooves 34 of the part 30.

FIGS. 8 and 9 show the front part 32 of the mouthpiece 12, viz. FIG. 9is a view in the direction of arrow D of FIG. 8. Here too, the feedchannels 23 for the reinforcing ribbons of the second layer are formedin assembled state between the conical inner face 38 and the grooves 37of part 31. In line with the channels 23 are provided guide grooves 39in the section 21" of the bore 21 whose diameter is once more enlarged,said grooves serving to guide the fed ribbons at a predetermineddistance from the longitudinal axis. Further more, radial slots 40 passbetween the grooves 39 into the bore part 21", in order to allow plasticsubstance to penetrate between the inner tube and the ribbons of thechannels or grooves 38, 39.

It is to be noted that more feed channels could of course be providedfor strand-like reinforcing layers, in order for example to form a thirdreinforcing layer lying further to the outside as viewed radially.

Instead of the ribbon-shaped reinforcing material, wires or cords couldalso be used.

Of course, the number of feed channels may also be chosen as desired.

What I claim is: v

1. An extruder for making strand reinforced tubing comprising:

a mouthpiece having an inner wall defining a central bore with an inletand an outlet end,

a guide passing through said central bore to define therewith an annulartube-forming cavity having an entry and exit end,

structure defining a first chamber, said first chamber communicatingwith said inlet end of said mouthpiece bore and containing plasticsubstance for partially forming said tube in said annular cavity whensaid plastic substance is input to said annular cavity from said firstchamber via said inlet end, initiation of said partial tube formationbeing at a point intermediate said entry and exit ends of said annularcavity,

said mouthpiece having feed channels intersecting said central boreinner wall and which has an output end communicating with said annularcavity at a location both between said entry and exit ends thereof anddownstream of said intermediate point whereat said tube initiatesformation, feed channels for ribbonor thread-like reinforcing material,which channels pass through the bore wall into the central bore in tworadial planes lying at a distance from one another, the channels of thesecond plane, observed in direction of transit of the tubing, openinginto a section of the bore with an enlarged diameter, strand-likereinforcing material in said feed channel for feeding said reinforcingmaterial onto the outer surface of said partially formed tube andthereby reinforcing it, and

structure defining a second chamber, said structure including a dischaving a central bore coaxial with said mouthpiece bore for giving saidpartially formed and reinforced tube an outer contour, said secondchamber communicating with said exit end of said tube-forming annularcavity and with said disc bore, said guide also passing through saiddisc bore.

2. An extruder head as claimed in claim 1 comprising front, central, andrear sleeves fitting inside one another on conical interfittingsurfaces, recesses being provided in the interfitting surfaces betweenthe rear and central sleeve and between the front and central sleeve forforming the said feed channels.

3. An extruder head as claimed in claim 1, wherein the said feedchannels consist of passages passing into the central bore anddistributed uniformly over the periphery of the mouthpiece, the passagesof the second plane being arranged in off-set relationship with respectto those of the first plane.

4. An extruder head as claimed in claim 3, wherein n feed channels openinto the central bore in each of the said radial planes at an angulardistance of 360ln, and wherein the angular distance, observed in thelongitudinal direction of the bore, amounts to 360l2n between thechannels of both planes.

5. An extruder head as claimed in claim 1, wherein there are providedslots in the section of the mouthpiece with enlarged bore, through whichplastic substance from the second chamber can penetrate into thisenlarged section in order to surround the strandlike reinforcingmaterial of the channels of the second plane.

1. An extruder for making strand reinforced tubing comprising: amouthpiece having an inner wall defining a central bore with an inletand an outlet end, a guide passing through said central bore to definetherewith an annular tube-forming cavity having an entry and exit end,structure defining a first chamber, said first chamber communicatingwith said inlet end of said mouthpiece bore and containing plasticsubstance for partially forming said tube in said annular cavity whensaid plastic substance is input to said annular cavity from said firstchamber via said inlet end, initiation of said partial tube formationbeing at a point intermediate said entry and exit ends of said annularcavity, said mouthpiece having feed channels intersecting said centralbore inner wall and which has an output end communicating with saidannular cavity at a location both between said entry and exit endsthereof and downstream of said intermediate point whereat said tubeinitiates formation, feed channels for ribbon- or thread-likereinforcing material, which channels pass through the bore wall into thecentral bore in two radial planes lying at a distance from one another,the channels of the second plane, observed in direction of transit ofthe tubing, opening into a section of the bore with an enlargeddiameter, strand-like reinforcing material in said feed channel forfeeding said reinforcing material onto the outer surface of saidpartially formed tube and thereby reinforcing it, and structure defininga second chamber, said structure including a disc having a central borecoaxial with said mouthpiece bore for giving said partially formed andreinforced tube an outer contour, said second chamber communicating withsaid exit end of said tube-forming annular cavity and with said discbore, said guide also passing through said disc bore.
 2. An extruderhead as claimed in claim 1 comprising front, central, and rear sleevesfitting inside one another on conical interfitting surfaces, recessesbeing provided in the interfitting surfacEs between the rear and centralsleeve and between the front and central sleeve for forming the saidfeed channels.
 3. An extruder head as claimed in claim 1, wherein thesaid feed channels consist of passages passing into the central bore anddistributed uniformly over the periphery of the mouthpiece, the passagesof the second plane being arranged in off-set relationship with respectto those of the first plane.
 4. An extruder head as claimed in claim 3,wherein n feed channels open into the central bore in each of the saidradial planes at an angular distance of 360*/n, and wherein the angulardistance, observed in the longitudinal direction of the bore, amounts to360*/2n between the channels of both planes.
 5. An extruder head asclaimed in claim 1, wherein there are provided slots in the section ofthe mouthpiece with enlarged bore, through which plastic substance fromthe second chamber can penetrate into this enlarged section in order tosurround the strand-like reinforcing material of the channels of thesecond plane.